1. Field of the Invention
The present invention relates to a sheet process device which once stacks received sheets of paper (simply referred as “sheets” hereinafter) on a first stack means and then shifts the stacked sheets to a second stack means.
2. Related Background Art
Conventionally, a device consisting of a combination of a process tray and a stack tray has been known as a sheet process device used in an image formation apparatus such as a copy machine, a printer or the like. On the process tray, sheets are stapled according to necessity. On the stack tray, sheets are received and stacked each sheaf.
In this sheet process device, a stapler to staple the sheets and a jogger to adjust or align the sheets with movement in front and rear directions are provided on the periphery of the process tray. Sheaves of sheets are adjusted on the process tray, the adjusted sheaves are respectively stapled, and the stapled sheaves are then discharged to the stack tray by a pair of sheaf discharge rollers.
Then, the stack tray is moved in forward and reverse directions (i.e., sheet-width direction) for each sheaf to sort over the sheaves of sheets. Moreover, the stack tray can be moved in upward and downward directions to fit a sheet face to the discharge roller.
However, the conventional sheet process device has following problems, and thus solutions for these problems have been earnestly expected. That is, in case of discharging the sheaf of sheets (paper) not yet stapled, if such the sheaves stacked on the process tray in large quantities are discharge at a time, the sheaves of sheets on the stack tray are off the alignment, whereby it becomes difficult to sort the sheets.
Further, in order to avoid a situation that, while the sheaves of sheets not stapled yet and stacked on the process tray are discharged to the stack tray, next or following sheets are fed to the process tray, it is necessary to temporarily stop an operation of the image formation apparatus itself during the sheet discharge operation.